Pivotal Tracker import fails with NoClassDefFoundError

Trying to import a project from Pivotal Tracker, fails. Import log contains:

2013-08-30 11:03:18,448 INFO - Import started by tim using com.atlassian.jira.plugins.importer.imports.pivotal.PivotalDataBean
2013-08-30 11:03:18,711 INFO - ------------------------------
2013-08-30 11:03:18,711 INFO - Importing: Users
2013-08-30 11:03:18,711 INFO - ------------------------------
2013-08-30 11:03:18,711 INFO - Only new items will be imported
2013-08-30 11:03:18,961 INFO - 3 users associated with import.
2013-08-30 11:03:18,980 INFO - ------------------------------
2013-08-30 11:03:18,980 INFO - Finished Importing : Users
2013-08-30 11:03:18,980 INFO - ------------------------------
2013-08-30 11:03:18,981 INFO - 0 users successfully created.
2013-08-30 11:03:18,981 INFO - Retrieving projects...
2013-08-30 11:03:19,557 ERROR - Unexpected failure occurred. Importer will stop immediately. Data maybe in an unstable state
java.lang.NoClassDefFoundError: com/atlassian/greenhopper/api/rapid/view/RapidViewCreationService
at com.atlassian.jira.plugins.importer.imports.pivotal.PivotalRapidBoardManager.createRapidBoard(PivotalRapidBoardManager.java:78)
at com.atlassian.jira.plugins.importer.imports.pivotal.PivotalDataBean$3.afterProjectCreated(PivotalDataBean.java:353)
at com.atlassian.jira.plugins.importer.imports.importer.impl.DefaultJiraDataImporter.importProject(DefaultJiraDataImporter.java:688)
at com.atlassian.jira.plugins.importer.imports.importer.impl.DefaultJiraDataImporter.doImport(DefaultJiraDataImporter.java:367)
at com.atlassian.jira.plugins.importer.imports.importer.impl.ImporterCallable.call(ImporterCallable.java:26)
at com.atlassian.jira.plugins.importer.imports.importer.impl.ImporterCallable.call(ImporterCallable.java:15)
at com.atlassian.jira.task.TaskManagerImpl$TaskCallableDecorator.call(TaskManagerImpl.java:365)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at com.atlassian.jira.task.ForkedThreadExecutor$ForkedRunnableDecorator.run(ForkedThreadExecutor.java:249)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.ClassNotFoundException: com.atlassian.greenhopper.api.rapid.view.RapidViewCreationService
at org.apache.felix.framework.ModuleImpl.findClassOrResourceByDelegation(ModuleImpl.java:772)
at org.apache.felix.framework.ModuleImpl.access$200(ModuleImpl.java:73)
at org.apache.felix.framework.ModuleImpl$ModuleClassLoader.loadClass(ModuleImpl.java:1690)
at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
... 14 more
2013-08-30 11:03:19,564 INFO - No issues need to be reindexed.